Grease compositions containing mixtures of ammonium dimethyldibenzyl bentonite and ammonium dimethyldioctadecyl bentonite clays as thickening agents



United States Patent M 3,449,248 GREASE COMPOSITIONS CONTAINING MIX- TURES OF AMMONIUM DIMETHYLDI- BENZYL BENTONITE AND AMMONIUM DI- METHYLDIOCTADECYL BENTONITE CLAYS AS THICKENING AGENTS Richard A. Butcosk, Westmont, N.J., assignor to Mobil Oil Corporation, a corporation of New York No Drawing. Filed June 1, 1967, Ser. No. 642,687

Int. Cl. 'C10m 5/04 U.S. Cl. 25221 11 Claims ABSTRACT OF THE DISCLOSURE Grease compositions are provided which contain greaseforming quantities of a thickening agent comprising a mixture of an ammonium dimethyldibenzyl bentonite clay and an ammonium dimethyldioctadecyl bentonite clay.

BACKGROUND OF THE INVENTION Field of the invention Description of the prior art Prior to the present invention, it was found that certain grease compositions tend to result in the vehicle, or components comprising the vehicle, separating under elevated temperature operating conditions. Such high degree of vehicle separation, or bleeding, is particularly apparent when the grease composition is subjected to operating conditions in which temperatures of about 350 F. or higher are encountered. This degree of vehicle separation at specified temperature operating conditions is dependent upon the specific vehicle, or combination of vehicles employed, and may result in vehicle separation to the extent of 20 percent or higher. In contrast, greases in Which vehicle separation of not more than about 5 percent occurs under conditions of operation are generally considered satisfactory. The ability to provide a grease in which vehicle separation at elevated temperature operating conditions is maintained at a relatively low level is, therefore, highly desirable.

SUMMARY OF THE INVENTION It has now been found, as more fully hereinafter described, in accordance with the present invention, that grease compositions can be provided in which separation of the vehicle or vehicle components can be maintained at a satisfactorily low level when subjected to elevated temperature operating conditions. This relatively low level of vehicle separation is achieved through the use of a grease-forming quantity of a thickening agent comprising a mixture of an ammonium dimethyldibenzyl bentonite clay and an ammonium dimethyldioctadecyl bentonite clay, as more fully hereinafter described.

'Prior to the present invention, the prior art has suggested the use of bentonite-type clays as grease thickeners. In this respect, I have found that vehicle separation, or separation of components comprising the vehicle, tends 3,449,248 Patented June 10, 1969 to occur to a relatively high degree when the grease is subjected to elevated temperature operating conditions, the actual degree of separation, or bleeding, depending in any specific instance upon the nature of the vehicle and clay thickener components present. On the other hand, I have also found that when the thickening agent comprises a mixture of the aforementioned ammonium dimethyldibenzyl and ammonium dimethyldioctadecyl bentonite clays in a weight ratio from about 2:1 to about 10:1, and preferably in a weight ratio from about 3:1 to about 5:1, vehicle separation does not occur to a relatively high degree even though the total quantity of the aforementioned clays present is not greater than the quantity of each clay component present when employed separately as thickening agents in the same grease composition.

The lubricating vehicles employed in the grease compositions of the present invention can comprise any of the conventional oils of lubricating viscosity, including mineral or synthetic lubricating oils. Mineral lubricating oils can be of any suitable lubricating viscosity ranging from about 45 SUS at F. to about 3500 SUS at 100 F., and preferably from about 50 to about 250 SUS at 210 F. These oils may have viscosity indexes varying from below 0 to about 13 0 or higher. Other hydrocarbon oils include synthetic hydrocarbon polymers having improved viscosity indexes, which polymers are prepared by polymerizing an olefin or mixtures of olefins having from 5 to 18 carbon atoms per molecule in the presence of an aliphatic halide and a Ziegler-type catalyst. Such hydrocarbon oils are described by Armstrong et al. in application U.S. Ser. No. 314,575, filed Sept. 26, 1963, now abandoned.

The lubricating vehicles employed in the novel grease compositions of the present invention can also comprise, as previously indicated, synthetic lubricating oils such as polypropylene, polypropylene glycol, di-(Z-ethylhexyl) sebacate, di-(Z-ethylhexyl) adipate and related adipates, dibutyl phthalate, polyethylene glycol, di-(Z-ethyl hexoate) and polysiloxanes (silicones). An important type of synthetic vehicle that may be employed in conjunction with mineral lubricating oils as a combination of vehicles are esters such as trimethylol propane esters, neopentyl esters and pentaerythritol esters. Other synthetic ester lubricants may include esters of adipic acid and isooctyl and isodecyl alcohols.

It is often advantageous to include in the novel grease compositions of the present invention stabilizing agents such as pentaerythritol or an anhydroenneaheptitol. Other improving agents can also be included in the grease compositions of this invention in order to obtain the benefit of their known characterizing features. For such purpose, antioxidants can be used, such as amines, mixtures of amines, and mixtures of amines and phenols, for example, a mixture of dioctyl phenyl amine and 4,4'-met hylene 'bis (2,6-ditertiarybutylphenol). Phenyl alpha naphthylamine (PAN) is preferred. Lubricity improving agents such as free fat, free fatty acids, sulfurized fats, lead soaps and various esters of alkyl and/ or acids can be employed. Rust and corrosion inhibitors such as sodium nitritate are also suitable for use in the novel grease compositions. As corrosion inhibitors, particularly preferred are compositions consisting essentially of (a) a product produced by neutralizing an N-carboxymethyl-alkenyl-succinamic acid, where the alkenyl group contains from about 8 to about 35 carbon atoms, with an alkali metal phosphate, in which the product has a pH of at least 7, and (b) an alkali metal nitrite. In this particular corrosion inhibiting composition, the N-carboxymethylalkenyl-succinamic acid is generally present in an amount from about 5 to about 70 percent, and preferably from about 25 to about 40 percent, by weight. The alkali metal phosphate is generally present in an amount from about 3 to about 70, and preferably from about to about 50 percent, by weight. The alkali metal nitrite is generally present in an amount from about 5 to about 70 and preferably from about to about percent, by weight. The corrosion inhibitor, itself, is preferably employed in an amount from about 0.2 to about 5 percent, by weight, of the total grease composition. Particularly preferred as components of the aforementioned corrosion inhibitor are compositions consisting essentially of the reaction product of (a) N-carboxymethyl-tetrapropenyl-succinamic acid and sodium phosphate, and b) sodium nitrite. The aforementioned thickening agents of the present invention comprising a mixture of the ammonium dimethyldibenzyl and ammonium dimethyldioctadecyl bentonite clays are employed in a grease-forming quantity. Particularly preferred are grease compositions in which the aforementioned novel thickener is present in an amount from about 5 to about 20 percent, by weight, of the total weight of the grease composition.

The grease compositions of the present invention can be prepared in accordance with conventional grease manufacturing procedures, in which the thickening agent comprising "a mixture of the ammonium dimethyldibenzyl and ammonium dimethyldioctadecyl bentonite clays is thoroughly admixed with the grease vehicle (including other ously indicated, can be employed and will be readily ap* parent to those skilled in the art.

A series of three-pound grease batches was subjected to a standard test for determination of the degree of vehicle separation, according to Federal Method VVL No. 791-321, as shown in the examples of the following table. Grease A, as shown in the table, contained as the vehicle an ester fluid, viz, the tricaprylate of trimethylol propane, and, as the thickening agent, ammonium dimethylidocta decyl bentonite clay. Grease B contained the same thickening agent as Grease A except that a mineral oil was employed as the vehicle. This mineral oil was a 155 SUS at 210 F., and 2650 SUS at 100 F. oil and had a flash point of 550 F. Greases C and D are identical to Greases A and B, respectively, except that ammonium dimethyldibenzyl bentonite clay is employed as the thickening agent. Grease E contains a mixture of the aforementioned ammonium dimethyldibenzyl and ammonium dimethyldioctadecyl bentonite clays as the thickening agent, and, as the vehicle, a mixture of the aforementioned ester of tricaprylate of trimethylol propane and the aforementioned mineral oil. Each of the greases tested contained additional additives in the total amounts indicated in the table to comprise the balance of the grease formulation. These additives comprised a mixture of small amounts of corrosion inhibitors, phenolic and amine-type anti-oxidants, polyol-type stabilizers and a dye.

TABLE Example Grease Formula A B C D E Ammonium dimethyldibenzyl bentonite clay (wt. percent) 9. 0 9. 0 6. 3 Ammonium dimethyldioctadecyl bentonite clay (wt. percent) 9. 0 9. 0 2. 7 Ester (wt. percent) 80.0 56. 0 Mineral Oil (wt. percent) 80. 0 80. 0 24. 0 Additives (wt. percent) Balance Balance Balance Balance Balance Properties:

NL GI consistency grade- 0000 1% 2 1 2% Penetration, u/w Fluid 300/305 160/270 323/330 251/256 Oil separation at 350 F (wt. percent) 100 8. 7 5.1 16.7 4. 0

desired additives), and the resulting grease composition being subjected to homogenization employing such equipment as a Manton Gaulin Homogenizer. If so desired, the aforementioned other additives can also be incorporated in the grease composition following homogenization. Where the grease vehicle comprises, for example, a mineral oil and an ester-type fluid, as hereinbefore indicated, a preferred manufacturing technique is to separately incorporate the dimethyldibenzyl ammonium bentonite clay in the ester fluid, separately incorporate the dimethyldioctadecyl bentonite clay in the mineral oil, and then combining the two mixtures to provide a grease composition in which minimum separation of vehicle components under elevated temperature operating conditions takes place.

DESCRIPTION OF SPECIFIC EMBODIMENTS The following data and examples will serve to illustrate the preparation of the novel grease compositions of the present invention and their efficacy in minimizing vehicle separation by employing the aforementioned novel combination of ammonium dimethyldibenzyl and ammonium dimethyldioctadecyl bentonite clays as thickening agents. It will be understood, however, that it is not intended that the invention by limited to a particular combination of the aforementioned bentonite clays as thickening agents or the particular grease compositions containing such thickening agents, as described. Various modifications of these grease compositions and thickening agents, as previ- It will be apparent from the data and examples set forth in the above table that the use of the ammonium dimethyldioctadecyl bentoniate clay alone as the thickening agent (Grease A) results in a fluid composition with complete separation of the ester vehicle, rendering the grease unsuitable for use at the elevated temperature of 350 F. Grease B, which contains the same individual clay thickener but employs the mineral oil as the vehicle, also was unsatisfactory because of the relatively high degree of oil separation, viz, 8.7 percent, under the conditions of the test. Greases C and D, which are identical to Greases A and B, respectively, except that ammonium dimethyldibenzyl bentonite clay is employed as the thickening agent, as previously indicated, when subjected to the test, revealed that when the vehicle comprises the ester fluid, the degree of vehicle separation is approaching a satisfactory rating (Grease C); whereas when the vehicle comprises the mineral oil, and unsatisfactory degree of vehicle separation occurs, viz, 16.7 percent. On the other hand, when the vehicle comprises a combination of the aforementioned ester fluid and mineral oil, and when a mixture of the aforementioned ammonium dimethyldibenzyl and ammonium dimethyldioctadecyl bentonite clays is employed as the thickening agent as shown in Grease E, the degree of vehicle separation under the conditions of the test is only 4.0 percent, and thus represents a significantly satisfactory reading.

Although the present invention has been described with preferred embodiments, it will be understood that various modifications and adaptations thereof may be resorted to without departing from the spirit and scope of the invention.

I claim:

1. A grease composition containing synergistic proportions of a grease-forming quantity of a thickening agent comprising a mixture of an ammonium dimethyldibenzyl bentonite clay and an ammonium dimethyldioctadecyl bentonite clay in a weight ratio from about 2:1 to about :1 and a vehicle comprising a mineral oil of lubricating viscosity and a carboxylic acid ester fluid.

2. A grease composition as defined by claim 1 wherein said ammonium dimethyldibenzyl bentonite clay and ammonium dimethyldioctadecyl bentonite clay are present in a weight ratio from about 3:1 to about 5:1.

3. A grease composition as defined by claim 1 wherein the ester comprises the tricaprylate of trimethylol propane.

4. A grease composition as defined by claim 1 containing as a corrosion inhibitor a composition consisting essentially of (a) a product produced by neutralizing an N- carboxymethyl-alkenyl succinamic acid, said alkenyl group containing from about 8 to about 35 carbon atoms, with an alkali metal phosphate, said product having a pH of at least 7, and (b) an alkali metal nitrite.

5. A grease composition as defined by claim 4 wherein said alkenyl group contains from about 10 to about 14 carbon atoms.

6. A grease composition as defined by claim 4 wherein said N-carboxymethyl-alkenyl succinamic acid is N-carboxymethyltetrapropenyl succinamic acid, said alkali metal phosphate is sodium phosphate and said alkali metal nitrite is sodium nitrite.

7. A grease composition as defined by claim 4 wherein said N-carboxymethyl alkenyl succinamic acid is present in said corrosion inhibitor in an amount from about 5 to about 70 percent, by weight, said alkali metal phosphate is present in an amount from about 3 to about 70 percent, by weight; and said alkali metal nitrite is present in an amount from about 5 to about 70 percent, by weight.

8. A grease composition as defined by claim 4 wherein said N-carboxymethyl alkenyl succinamic acid is present in said corrosion inhibitor in an amount from about 25 to about percent, by weight; said alkali metal phosphate is present in an amount from about 25 to about percent, by weight; and said alkali metal nitrite is present in an amount from about 30 to about 50 percent, by weight.

9. A grease composition as defined by claim 4 wherein said corrosion inhibitor is present in an amount from about 0.2 to about 5.0 percent, by weight, of the total grease.

10. A composition comprising a mixture of an ammonium dimethyldibenzyl bentonite clay and an ammonium dimethyldioctadecyl bentonite clay in a weight ratio from about 2:1 to about 10:1.

11. A composition as defined by claim 10 wherein said ammonium dimethyldibenzyl bentonite clay and said ammonium dimethyldioctadecyl bentonite clay are present in a weight ratio from about 3:1 to about 5:1.

References Cited UNITED STATES PATENTS 2,966,506 12/1960 Jordan 25228 3,296,127 1/1967 Butcosk et a1. 25225 3,349,034 10/ 1967 Butcosk et a1. 25228 DANIEL E. WYMAN, Primary Examiner.

I. VAUGHN, Assistant Examiner.

US. Cl. X.R. 2 52-28 

